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Growth, survival, isolation and incidence of Y. enterocolitica in foods and other materials.

Kendall, Margaret. (1982) Growth, survival, isolation and incidence of Y. enterocolitica in foods and other materials. Doctoral thesis, University of Surrey (United Kingdom)..

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5 organisms/ml after48 h. Yersinia enterocolitica inoculated into boiled fish, egg, potato, rice, roast chicken and chocolate milk grew readily at all temperatures from 4 - 37°C. The organism survived without any change in count, for at least 8-9 weeks in these foods whilst stored at -20°C. Yersinia enterocolitica did not effect the pH of the food in which it was growing. The organism did not grow when inoculated into six mayonnaise sauces, with pH values of 2.9 - 4.8. Evaluations were made of agar and broth media and methods for the isolation of Y. enterocolitica from foods and other materials. Sixteen media commonly used for the isolation of other pathogens were compared with some eight media specially formulated for Y. enterocolitica. No medium was shown to be ideal. In an attempt to formulate or modify a new isolation medium the effects of dyes and other selective agents on the growth of Y. enterocolitica and other organisms was studied. Malachite green (0. 004%) incorporated into deoxycholate citrate sucrose agar was found to be inhibitory for many enterobacteria but not for Y. enterocolitica. This effect was shown to be related to the ratio of malachite green to sodium deoxycholate. Five studies involving 1004 foods and other materials were carried out to further evaluate various media and methods for the isolation of Y. enterocolitica as well as to investigate the incidence of the organism. The highest isolation rate was obtained from buffered peptone water incubated at 4°C and sub-cultured to lactose sucrose urea agar. Biochemical characterization and antibiotic sensitivity patterns were determined for all the presumptive Y. enterocolitica strains and the isolation of Y. enterocolitica sensu stricto was confirmed from 53 of 1004 (5. 3%) samples including 13/67 pasteurized milk, 7/119 beef, 16/159 pork, 6/40 sausages, 4/101 raw chicken, 4/14 sewer swabs, 2/140 animal feed and 1/1 cooked ham. Yersinia intermedia was isolated from seven samples and Y. frederiksenii from three samples. There was no significant difference in the antibiotic sensitivity patterns of the three species. Fourteen different serotypes were identified of which serotype 0:5 was the most commonly isolated. Other serotypes included 0:5,27, 0:6,30 and 0:8 each of which have been implicated in human illness. A few strains were rough and could not be serotyped and 17% of the isolates were not typable with the available antisera. Some foods contained multiple serotypes.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Kendall, Margaret.
Date : 1982
Contributors :
Additional Information : Thesis (M.Phil.)--University of Surrey (United Kingdom), 1982.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 13:55
Last Modified : 06 Nov 2018 16:52

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